1. Field of the Invention
The present invention relates generally to mitigating tape media damage. More particularly, the present invention relates to a method and apparatus for shifting the wrap turn around/stream points in a tape media to an unused region of tape, thereby controlling where edge damage occurs.
2. Background of the Invention
Magnetic tapes, including reel and cassette-style cartridges and other devices that use magnetic media, are used in many industries to store data, programs, and other information. Magnetic tapes are typically stored on reels or spools, which are cylinders about which the tape is wound, typically having flanges to guide the tape onto the cylinder. Accessing information from a reel or spool of tape typically requires that the spool be inserted into a reading machine, which unwinds the tape from the file spool and winds it onto a temporary storage spool (also referred to as a machine reel or machine spool) until the portion of the tape with the desired information is reached. A magnetic read element reads the information, and the tape is rewound back onto the original file spool and removed from the reader.
A problem with tape media, especially with single reel media cartridges, is the propensity for edge damage to cause loss of data. Edge damage typically arises from the occurrence of a popped strand. A popped strand is a section of the wound tape not in alignment with the rest of the tape. Popped strands usually occur when the tape drive performs a start or stop operation. When the tape is started again or is stopped, the tape may experience movement in a direction perpendicular to normal tape motion as the tape is brought up to speed or when the tape is stopped. This lateral tape motion may result in a popped strand.
On a typical spool holding the magnetic tape, the spacing between the upper and lower flexible flanges of the spools (both the file spool and the machine spool) is wider than the nominal width of the tape. As the tape is fed onto these spools, lateral tape motion may occur during a start or stop operation, and a popped strand may result. The popped strand itself does not cause tape edge damage. Rather, tape edge damage may be caused when the flexible flange is forced against the popped strand during shipment or rough handling, such as if the spool is dropped. If the edge damage is severe, track following capability may be lost and the head to tape spacing may increase to the point where data cannot be read back.
As tape media construction is getting thinner, the tape will be more prone to edge damage. This tape may fail at customer sites due to edge damage near the beginning of tape (BOT). An ideal solution to lessen tape damage would be to eliminate the occurrence of popped strands. One such technique includes performing a high-speed rewind through the wrap turn around points to reduce the number of popped strands, thereby minimizing the potential for tape edge damage. However, as this technique still does not eliminate popped strands entirely, tape edge damage may still occur in data regions and tape format regions.
Thus, it would be advantageous to have a method and apparatus for controlling where popped strands occur to mitigate tape edge damage.